We report the shock‐wave synthesis at a yield ≳80% by volume of the single copper layer thalliumsuperconductor of composition Tl2Ba2CuO6. The as‐synthesized material displays zero resistance near 55 K and a diamagnetic onset to bulk superconductivity at 70 K. Lattice imaging indicates that the superconducting microcrystals consist of a novel defect microstructure involving an intergrowth of two copper‐oxygen layers probably interleaved by partial thallium and barium occupancy.